This invention concerns a method for removing undesirable haze from distillate fuels, such as diesel fuels, heating oils and fuels for jet aircraft. The haze, which results from the formation of a water-in-oil emulsion where only slight traces of water remain in the fuel, constitutes a frequent problem in the marketing of such fuels. There is always the danger that the water present in such haze, which may represent about 100 to 300 parts per million of water in the fuel, will coalesce in later storage and cause corrosion and operating problems, including ice formation under winter conditions. Also, even in those cases where the haze may not present any particular problem from the technical standpoint, i.e., it may not interfere with the practical use of the fuel, it is nevertheless objectionable from the marketing standpoint because of the undesirable appearance imparted to the fuel when the haze is present. It is almost impossible to prevent the formation of such haze because an aqueous phase exists in most fuel storage tanks as a result of moisture condensation from the venting atmosphere in the tank.
Briefly, in the practice of the present invention, a small amount of an inorganic salt, dissolved in a solvent comprising an aliphatic hydroxy compound that is well miscible with water but not miscible with a distillate fuel is added to and mixed with the hazy fuel, causing the haze to clear up much more rapidly than would occur by simply allowing the water to settle out of the fuel, the latter frequently taking much longer than could be practically tolerated.